When I add my yahoo email, I forgot to disable address book. It ended up synced with it which is completely out of date. I deleted all entries from there. But in option, I can still see it listed. How can I remove it completely? I've already tried to remove the yahoo email account altogether.

You should probably delete your Yahoo email account, then all the Yahoo service books. After that, and a battery pull, you can add the Yahoo email account back, taking care NOT to enable syncing the address book.